JDS Labs Atom Amp+
Our job is to help you enjoy exceptional headphones. What we explained when announcing Atom Amp still holds true: We do not release new hardware for the sake of release schedules or corporate goals. In fact, this announcement was not on our roadmap and JDS Labs is doing well without the need to grab your attention. Of tens of thousands of Atom Amp owners, virtually no one has asked for more performance. Alas, we’ve continuously improved Atom Amp and it’s no longer accurate to call Atom Amp just an Atom Amp.
Atom Amp is now Atom Amp+, our best value amplifier. Aside from subtle fit and finish improvements since release, we’re tagging “Atom Amp+” because we’ve boosted performance using the same analog IC employed in the matching Atom DAC+. More importantly, every Atom Amp+ is built with hand matched potentiometers for superior low volume imaging, up to 20dB better than the originally spec’ed Alps pots.
Atom Amp+ remains only $99 USD!
Hardware Choices
Atom Amp+ is built on the exact same circuit board as Atom Amp. The bulk of the performance boost results from upgrading the input stage ICs from NJM2068 to NJM5532, followed by small tweaks to supporting resistors.
You’d expect this material cost increase and 20% global inflation to increase the price tag. Good news: We’ve moved Atom Amp+ PCB assembly from California to Illinois USA. This is not a corner cutting change. Rather, we’re super excited to partner with a growing CM who shares our manufacturing passion for constant improvement through automation. The transition has reduced freight costs and improved delivery speed. Yield is higher than ever, with zero defects found in the first thousand Atom Amp+’s.
Power: Atom Amp+ renders the same clean output power as the original, which is more than enough for over 99.9% of listeners. JDS Labs actively opposes shipping larger transformers to realize vastly unnecessary power specs. We understand our reasonable customers would even prefer to see smaller transformers. We’re confident Atom Amp+ strikes the right balance of enough power, and not too much. We made no changes to the output stage. Retuning the input stage slightly increased maximum output voltage at higher headphone impedances.
Enclosures: Fit and finish has come a long way since release. Of all the constructive feedback we’ve received, the general consensus is that some fingers prefer a beefier knob. Extra weights are still free upon request. If aftermarket knobs are not your thing, there’s always EL Amp II+ in a CNC milled aluminum enclosure.
Potentiometers: We were not quite satisfied with the small improvements to our 2019 Alps potentiometers. We originally considered triple gain to help with lower volume listening, but recognized the potentiometer would remain an audible bottleneck. We ultimately commissioned another manufacturer to produce custom potentiometers for Atom. Gangs are hand matched for tighter L/R balance to levels ~20dB lower than Alps was able to offer. All Atom Amps built since May 2020 feature our custom pots, so we’ve already accumulated a wealth of feedback to verify consistency and reliability. This important improvement is standard in Atom Amp+.
Performance
Atom Amp+ achieves a crazy 119dB SINAD @ 20-20kHz BW. This is around 6dB better than the initial release. Totally inaudible, by the way.
It’s possible to reach 120-122dB SINAD by omitting Atom’s high pass input filter, but there’s no incentive to do so. We know customers appreciate RFI rejection from the high pass filter and prefer a distraction free listening experience.
| Atom Amp | Atom Amp+ | |
| Frequency Response, 20Hz-20kHz | +/- 0.01dB | +/- 0.01dB |
| SINAD @ 2VRMS, 1kHz | 113 dB | 119 dB |
| SINAD @ 50mV, 1kHz | 90 dB | 90 dB |
| IMD SMPTE | -94 dB | -95 dB |
| Noise (20-20kHz) | 2.02 μV | 1.99 μV |
| Crosstalk @ 10kHz | -86 dB | -92 dB |
| SNR (20-20kHz) | > 122 dB | > 122 dB |
| Dynamic Range (AES17) | > 120 dB | > 120 dB |
| Input Impedance | 10k Ω | 10k Ω |
| Output Impedance | 0.1 Ω | 0.1 Ω |
| Max Continuous Power @ 600Ω | 125mW (8.68 VRMS) | 136mW (9.05VRMS) |
| Max Continuous Power @ 150Ω | 502 mW (8.66 VRMS) | 545 mW (9.04VRMS) |
| Max Continuous Power @ 32Ω | 1 Watt (5.66 VRMS) | 1 Watt (5.66 VRMS) |
Availability
Atom Amp+ is In Stock today at 99 USD. For those who ordered Atom Amp after May 28th 2021, you received a free upgrade to Atom Amp+ in an enclosure labelled as Atom Amp.
While inventory allows, Atom Amp+ boards in brand new enclosures labelled ‘Atom Amp’ are available in the B-Stock listing at only 89 USD.
Enjoy!
Hi there, so I ordered the atom amp today before the atom amp plus came out, will I receive the new plus model?
Hi Tom – Yes, your amplifier contains an Atom Amp+ board. The enclosure label will be match what is shown in your Order Confirmation email.
Awww I guess I must have gotten unlucky, I ordered mine on June 28th and got it today but I got the Atom Amp.
Please check again: You received Atom Amp+ in an enclosure labelled as Atom Amp!
Ohhh my bad! I misread the post towards the end. Thank you! The Atom Amp is my first amp and my Sundara sounds amazing because of it. Cheers!
Wow! JDS again show how a composite amplifier implemented cleanly can achieve state of the art performance.
Yeah, usually the linearity of the composite amplifier depends heavily on the classical one, not the output driver. I wonder what performance level Atom++ could achieve when OPA1612 is used.
On the power supply side, perhaps in the future JDS can transit to use switch mode power supply. It works in all countries, produce very little heat, and can be implemented very cleanly. Producing negative rail might need some extra work but could be easily resolved.
Thank you! OPA1612 is a fine option given a sufficient BOM budget.
Yes, I’d also like to move away from AC transformers. They’re a shipping burden. Ground loop problems tend to be more prevalent when moving to switching designs, so this must be taken into consideration.
maybe you can experiment it with a dac+hpamp combo unit first so there will be no ground loop issues (as long as USB ground is isolated).
also moving to balanced inputs (and keep the SE outputs as is) for amps and to balance outputs for DACs solve ground loop issues entirely.
I have no major issues with ultra high quality switching power supplies as I use some of them for my guitar pedals. The issue with lower quality switchers is that they can be very noisy. I can’t tell you how many times I literally threw out switching power supplies when, after a few months of use, they started emitting coil whine that would drive me nuts. Therefore, it would be paramount to select a really high quality switching power supply.
I say keep it simple and stay with the AC transformer.
Oh btw, I know under 99.99% conditions it’s not an issue, since the Atom amp is DC coupled throughout, will you consider adding dc protection circuit to the next product in the future? You already have mute relay there, doing dc detection for both channels only requires 4 resistors, 3 BJT transistors, and 1 cap, at most. So total addition to the cost is under half dollar.
@reminisce1989 – Thanks for the thought. We’re building on a larger scale. At 20k+ Atoms, that’s a $10,000 change. As far as I know, only one customer has managed to destroy his headphones with a broken DAC (not ours). We bought him new headphones for far below $10k.
imho calculation like this does make a lot of sense in theory but ignores how things in real world actually work.
similar to no one would actually need a -120db thd+n amp or a super high res dac in theory, but people are still buying them.
such features / differentiators make the product single out in the competition.
another example is, a pcb made in the US or China probably won’t have any difference at all.
but “proudly made in America” is something many JDS customers are looking for.
The same goes to protection circuits.
Darn I was so close by a few days, ordered mines on May 24 XD
Hello, I would like to ask you whether overseas buyers also have upgrade services?
How can I use this service? Thank you!
Hi John,
I was wondering if SINAD only used 1khz as a data point and was measured at other parts of the frequency range? what about sending in a wave at 37hz and 8khz?
thank you
@Yannick – Yes, SINAD is published at 1kHz. Keep in mind THD+N is the reciprocal of SINAD, and we always perform a routine THD+N sweep from 20-20kHz for development and first article testing. This should be added to specs (why not!)
“We always perform a routine THD+N sweep from 20-20kHz for development and first article testing.”
Awesome, is that spec consistent across 20-20khz? 😀
THD+N / SINAD typically varies with frequency, but not much in a good design.
From 20-20kHz, Atom Amp+ stays around 119dB SINAD at most frequencies and relaxes to about 115dB @ 10kHz, still outperforming the original Atom Amp across the board 🙂
Thank you so much for your transparency John!
Hi there,
i’m producing, mixing and mastering my own music and currently use a Focusrite Scarlett 8i6 audio interface and Sennheiser HD 650 connected to it.
Would Atom+ be a suitable amp for these purposes and devices i use?
I’ve watched a video where it was said that the predecessor Objective2 worked really well with the HD 650.
Therefore i guess Atom+ would do so as well.
@Valentin – Yes, many customers use Atom Amp+ in conjunction with Focusrite interfaces. Atom is a clear upgrade over the retired Objective2.
Thank you, John. I’m curious now…
Oh mannnn, i got unlucky. I ordered on 23rd june and received the atom amp :”’)) it’s great tho but wish i knew about this
Please check the last section of the article: “you received a free upgrade to Atom Amp+ in an enclosure labelled as Atom Amp.”
Do you guys offer product upgrades if we send our old atom-amp back to change into an amp+ and how much would it cost?
I order on 30th June and received a Atom amp, nevermind anyway.
@FAN: Please check the last section of the article: “you received a free upgrade to Atom Amp+ in an enclosure labelled as Atom Amp.”
Does it also mean that if I changed the NJM2068 to NJM5532 or NE5532 in my Objective2, I would have an inaudible performance improvement as well?
@Jimmy – Check out the 2011 notes on this topic at: http://nwavguy.blogspot.com/2011/08/op-amp-measurements.html
Thanks for your reply, John. Yes, I have read that NwAvGuy’s article some times ago. If I interpreted him correctly, he found that both NJM2068 and NE5532 performed similarly in O2, and he picked NJM2068 as the default because of its lower cost.
Given you may have a better measuring equipment than NvAvGuy and you have opted to change NJM2068 to NJM5532 as an upgrade despite the higher cost, I am curious is the same benefit can be applied to O2.
Was NvAvGuy’s opamp findings limited by the performance of O2, or his dSCOPE (which NvAvGuy mentioned had a residual THD+N of 0.0005% / -106dB)?
Good thought. While I have not tested this exact setup, I expect the O2 was slightly limited by the NJM2068, but this is not the bottleneck in the older amp. The NJM4556 output stage limits performance more, both in terms of power and THD+N.
Hey John, could I email you? I need some help with my setup.
Would I be able to pair my original Atom Amp from last year to an Atom Dac+? And if so how would I do that?
@Alex – Yes, Atom DAC+ pairs perfectly with the original Atom Amp. We made sure to tune Atom DAC+ for backwards compatibility: Output voltage of Atom DAC+ is 2 VRMS, just like the original Atom DAC.
Wonder if there will be Atom line for equalizer? Like the Subjective3 but maybe 4 bands control.
Am I understanding correctly that if I ordered my Atom Amp back in February 2021, it at least has the improved volume pot of the Atom+ (assuming it was manufactured after May 2020 – it is B-stock, if that matters)?
Correct!
Awesome, thank you for the reply and the fantastic products!
Will there be Atom Amp+ and Atom DAC+ combo in one enclosure?
Thanks for the feedback, Andrew. Difficult to say at this time with IC shortages through 2022.
How do you go about requesting the additional weights when placing an order?
“JDS Labs actively opposes shipping larger transformers to realize vastly unnecessary power specs. ” does this mean we can use a larger power transformer to increase the atom’s power specs?
@Yannick – Yes, a few customers have experimented with larger transformers and have reported fine stability and increased power under low impedance loads. Keep in mind this is only anecdotal feedback. I have not vetted the claims, but am aware the 16V 1000mA transformers are the bottleneck under extreme loads.
If we were to use larger power transformers, we have to increase voltage or ma?
Keep the same 16VAC voltage rating, and only increase the current capacity (mA).
I have the Atom+ DAC and could not be happier with it. It is an excellent product.
My questions are:
What NJM op amps are used? 5532 or 4562? Or?
Any reason for choosing NJM over NE or TI?
Thank you.
Hi Gary – Atom DAC+ currently uses NJM5532MD.
NJM5532s consistently outperform the NE5532 branded versions. NJM4562 availability is poor in the US, and supply of TI parts has been unpredictable for the past 2 years (getting better). The OPA1692 is found in our new Element III.
If I wanted to replace the knob with one of the Taiss ones you recommended, how would I go about doing that? Is it as simple as just pulling the old knob clean off and sticking the other one straight on? Will this damage the pot or make the knob looser in any way?
@Jay – Yes, the original knob can be pulled off. The Taiss knob installs with a setscrew and included Allen wrench. The fit can be tight, so it may help to temporarily loosen the screws found beneath the four rubber feet, allowing the entire assembly to be repositioned. Atom Amp+’s built in 2022 also have alternative pads for moving the potentiometer forward. Of course, this modification is best accomplished at the time of assembly.
I just ordered today the JDS Atom Dac+ Hevi and was and already own the oringinal Atom Amp.
Do you recommend buying the Atom Amp+?
Will there be any difference in sound in upgrading to the Plus at all?
I was considering also purchasing the Amp+ Hevi today but just couldnt afford it today.
Hi Ray – Atom DAC+ HEVI is a solid upgrade. The original Atom Amp is still a solid amplifier–no audible need to upgrade unless you prefer the metal build.
Thank You for the reply.
I just might prefer the metal build….and make it a Hevi Stack…lol.